I found a lump in my breast...

[malignant Cysts]

I am 29, and I do not have any history of breast cancer.  I had an ultrasound completed and there are a cluster of cysts, but my doctor explained to me that because they are not the normal shape of a cyst, round, it could have cancer cells that have attached themselves to the cyst.  The measurement is 1cm by 2cm.  Does that mean the cancer cells came from a different part of the body?  Because they are not tumors, would that rule out breast cancer?  Is this common to find malignant cysts, and can you give me a web site for more information on malignant cysts?
Thank you.

[CCF-RN,MSN-rf]

Dear malignant Cysts:  In general, cysts are benign.  Since your cysts have some irregularity to them, your doctor would like to be certain that there is nothing else going on within the cysts - that there is nothing hiding in this "cluster."  IF this were to turn out to have malignant cells within or next to the cyst, it would most likely be breast cancer.  Breast cancer is simply breast cells that have become malignant.  You are very young and that makes a cancer diagnosis less likely but it is reasonable to invesitgate your cysts to make sure all is okay.

[surgeon]

it is extremely rare for cysts in the breast to due to, or to contain cancer. However, women who get cysts could get cancer, too, just because cysts are common enough that you can have both. In a 29 year-old with no family risk factors, cancer is uncommon. I assume the point the doctor was making is that if an area can be seen to be a simple, typical cyst, then generally there's nothing to worry about. If it looks like lots of little cysts, it's probably ok, too; but since the only clear-cut finding is when it's one or two very typical cysts, when some other pattern is seen they have to include the possibility of something else going on. So the choice becomes one of keeping a careful eye on things or having some sort of biopsy to be sure.